Effect of heating rubber stoppers on provoking allergic reactions in a subject sensitive to latex

9/17/2012
I am a school nurse involved in planning care for a student with a latex allergy. Past reactions have been to latex balloons (blowing them up). The science unit he is currently in includes a lab using latex tubing, glass vials, and rubber stoppers. The student is able to touch the products without a problem. We have decided to let him participate during the Practice Day, wearing non-latex gloves.

Our concern is for the following lab day, in which the tubing will be heated. I'm told that the stoppers become hot as well. The question is whether heating the latex will cause latex proteins to be released into the air. His allergist cannot say with certainty that there is no danger to the student. We are currently looking to purchase latex-free science lab equipment, but I'd like some feedback about heating the tubing/stoppers. Thank you.

A:

Thank you for your inquiry.

Unfortunately I cannot give you a definitive answer. To my knowledge we simply do not know for sure what effect heating latex tubing or stoppers would have on releasing latex allergen into the air. We do know that inhalation of latex can produce allergic reactions (1). However, we also know that at least some of the allergens responsible for latex allergic reactions are heat labile, and could therefore might be destroyed by heating (2) (Reference Number 2 and the abstract copied below).

However, what we do not know is whether or not latex would be released into the air from the rubber stoppers or the tubing. At least I could find no reference to this situation in the literature.

However, I am going to ask Dr. Jay Slater, who is an internationally known expert in latex allergy, and the author of Reference Number 2 cited below, to assist us in this regard. When I hear from Dr. Slater, I will forward his response to you.

Allerg Immunol (Paris). 1994 Jun;26(6):219-20.
[Latex allergy: is the allergen thermolabile?].
[Article in French]
Rat JP.
Abstract
The 30,000 dalton latex allergen is considered to be both hydrosoluble and thermolabile. Its thermolability does not seem to have been proved in various reviews. Three lots were prepared from an original soaking solution by different heating techniques. The prick-tests done with the three heated lots and with the original solution prove that, despite apparent contradictory results, the allergen is truly thermolabile. Could this thermolability trait be an explication for latex allergy?

Sincerely,
Phil Lieberman, M.D.

We received a response to your Ask the Expert inquiry from Dr. Jay Slater. Thank you again for your inquiry and we hope this response is helpful to you.

Sincerely,
Phil Lieberman, M.D.

Response from Dr. Jay Slater:
From the start there were questions about heat stability of latex proteins being an issue. It's been invoked (along with chemical modifications) as the reason for decreased reactivity to molded products (tires, most toys) compared to the dipped products (gloves, condoms, balloons).Even if we assume that heating dramatically reduces allergenicity, my concern here (as was yours) is that inadequately heated allergen might become volatilized and elicit a reaction. The next question is whether there would be enough allergen sent into the air to elicit a severe reaction. There are no papers on this - the only volatilized latex allergen studied is powder-based.

I would ask the following:
1. Is the rubber stopper the typical black rubber of chemistry labs? If so, these are neoprene rubber or bromobutyl rubber and would not be an issue. (The supply catalogue will have the answer).

2. The tubing could very well be latex. However these are extruded rubber products and their allergen content is probably low. Also, how hot will it get? If it's just baby bottle warm, I doubt that there will be an issue.

3. How severe were the patient's previous reactions?

Unfortunately there is no right answer. The local allergist is probably right to be conservative with his/her patient, but I'd probably phrase it differently: this does NOT appear to be a high-risk situation, and reasonable precautions (the removal of latex gloves) are being instituted, but the circumstance has not been studied so we cannot be really sure.